Here are two ways to convert a given Julian day to its date value in PostgreSQL.
The first method directly inputs the Julian day into the date data type.
The second method uses the to_date() function to return the same result.
Julian day is the number of days since Monday, January 1, 4713 BC using the proleptic Julian calendar, which is November 24, 4714 BC, in the proleptic Gregorian calendar.
Continue readingIn PostgreSQL, you can convert a given date to its Julian day representation by using the to_char() function.
To do this, pass the date as the first argument, and 'J' as the second.
In Postgres, you can use the to_char() function to return the century, based on a given date.
To do this, use CC as the second argument. This returns the two-digit century based on the date provided.
The PostgreSQL to_char() function provides us with the option of adding the ordinal number suffix to the result.
This means we can add the ordinal indicator when formatting dates.
For example, instead of outputting 10 Feb we could output 10th Feb.
Continue readingThis page contains the full list of template patterns and template pattern modifiers that can be used when formatting date and times in PostgreSQL.
Continue readingIn PostgreSQL, you can get the day name from a date by using the to_char() function. This function returns a string based on the timestamp and the template pattern you provide as arguments..
In PostgreSQL, you can use the to_char() function to get the short month name from a date.
By “short month name” I mean the abbreviated month name, for example Jan, Feb, Mar, etc.
The to_char() function accepts two parameters; the date and the format string with which to format that date.
In PostgreSQL you can use the extract() function to get the year from a date.
You can also use the date_part() function to do the same thing.
The SQLite strftime() function enables you to return a date and time value in a specified format.
The actual date/time value returned is based on a time string that you provide as an argument when you call the function, as well as any modifiers you include (as optional arguments). A modifier allows you to change the date, such as add a number of days, set it to local time, etc
Continue readingThe SQLite julianday() function returns the number of days since noon in Greenwich on November 24, 4714 B.C. (using the Proleptic Gregorian calendar).
If using the proleptic Julian calendar, this is Monday, January 1, 4713 BC.
Julian day is the continuous count of days since the beginning of the Julian Period. It’s typically used by astronomers, software, etc to calculate elapsed days between two events.
To use this function, you need to provide a time string, plus any (optional) modifiers. A modifier allows you to change the date, such as add a number of days, set it to local time, etc
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